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<FONT color="green">001</FONT>    /*<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<FONT color="green">003</FONT>     * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<FONT color="green">004</FONT>     * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<FONT color="green">005</FONT>     * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<FONT color="green">006</FONT>     * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<FONT color="green">007</FONT>     * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<FONT color="green">008</FONT>     *<a name="line.8"></a>
<FONT color="green">009</FONT>     *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<FONT color="green">010</FONT>     *<a name="line.10"></a>
<FONT color="green">011</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<FONT color="green">012</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<FONT color="green">013</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<FONT color="green">014</FONT>     * See the License for the specific language governing permissions and<a name="line.14"></a>
<FONT color="green">015</FONT>     * limitations under the License.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    package org.apache.commons.collections;<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    import java.util.ArrayList;<a name="line.19"></a>
<FONT color="green">020</FONT>    import java.util.EmptyStackException;<a name="line.20"></a>
<FONT color="green">021</FONT>    <a name="line.21"></a>
<FONT color="green">022</FONT>    /**<a name="line.22"></a>
<FONT color="green">023</FONT>     * An implementation of the {@link java.util.Stack} API that is based on an<a name="line.23"></a>
<FONT color="green">024</FONT>     * &lt;code&gt;ArrayList&lt;/code&gt; instead of a &lt;code&gt;Vector&lt;/code&gt;, so it is not<a name="line.24"></a>
<FONT color="green">025</FONT>     * synchronized to protect against multi-threaded access.  The implementation<a name="line.25"></a>
<FONT color="green">026</FONT>     * is therefore operates faster in environments where you do not need to<a name="line.26"></a>
<FONT color="green">027</FONT>     * worry about multiple thread contention.<a name="line.27"></a>
<FONT color="green">028</FONT>     * &lt;p&gt;<a name="line.28"></a>
<FONT color="green">029</FONT>     * The removal order of an &lt;code&gt;ArrayStack&lt;/code&gt; is based on insertion <a name="line.29"></a>
<FONT color="green">030</FONT>     * order: The most recently added element is removed first.  The iteration<a name="line.30"></a>
<FONT color="green">031</FONT>     * order is &lt;i&gt;not&lt;/i&gt; the same as the removal order.  The iterator returns<a name="line.31"></a>
<FONT color="green">032</FONT>     * elements from the bottom up, whereas the {@link #remove()} method removes<a name="line.32"></a>
<FONT color="green">033</FONT>     * them from the top down.<a name="line.33"></a>
<FONT color="green">034</FONT>     * &lt;p&gt;<a name="line.34"></a>
<FONT color="green">035</FONT>     * Unlike &lt;code&gt;Stack&lt;/code&gt;, &lt;code&gt;ArrayStack&lt;/code&gt; accepts null entries.<a name="line.35"></a>
<FONT color="green">036</FONT>     * &lt;p&gt;<a name="line.36"></a>
<FONT color="green">037</FONT>     * &lt;strong&gt;Note:&lt;/strong&gt; this class should be bytecode-identical to the <a name="line.37"></a>
<FONT color="green">038</FONT>     * version in commons collections. This is required to allow backwards <a name="line.38"></a>
<FONT color="green">039</FONT>     * compability with both previous versions of BeanUtils and also allow <a name="line.39"></a>
<FONT color="green">040</FONT>     * coexistance with both collections 2.1 and 3.0.<a name="line.40"></a>
<FONT color="green">041</FONT>     *<a name="line.41"></a>
<FONT color="green">042</FONT>     * @see java.util.Stack<a name="line.42"></a>
<FONT color="green">043</FONT>     * @since Commons Collections 1.0<a name="line.43"></a>
<FONT color="green">044</FONT>     * @version $Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $<a name="line.44"></a>
<FONT color="green">045</FONT>     * <a name="line.45"></a>
<FONT color="green">046</FONT>     * @author Craig R. McClanahan<a name="line.46"></a>
<FONT color="green">047</FONT>     * @author Paul Jack<a name="line.47"></a>
<FONT color="green">048</FONT>     * @author Stephen Colebourne<a name="line.48"></a>
<FONT color="green">049</FONT>     */<a name="line.49"></a>
<FONT color="green">050</FONT>    public class ArrayStack extends ArrayList implements Buffer {<a name="line.50"></a>
<FONT color="green">051</FONT>    <a name="line.51"></a>
<FONT color="green">052</FONT>        /** Ensure serialization compatibility */    <a name="line.52"></a>
<FONT color="green">053</FONT>        private static final long serialVersionUID = 2130079159931574599L;<a name="line.53"></a>
<FONT color="green">054</FONT>    <a name="line.54"></a>
<FONT color="green">055</FONT>        /**<a name="line.55"></a>
<FONT color="green">056</FONT>         * Constructs a new empty &lt;code&gt;ArrayStack&lt;/code&gt;. The initial size<a name="line.56"></a>
<FONT color="green">057</FONT>         * is controlled by &lt;code&gt;ArrayList&lt;/code&gt; and is currently 10.<a name="line.57"></a>
<FONT color="green">058</FONT>         */<a name="line.58"></a>
<FONT color="green">059</FONT>        public ArrayStack() {<a name="line.59"></a>
<FONT color="green">060</FONT>            super();<a name="line.60"></a>
<FONT color="green">061</FONT>        }<a name="line.61"></a>
<FONT color="green">062</FONT>    <a name="line.62"></a>
<FONT color="green">063</FONT>        /**<a name="line.63"></a>
<FONT color="green">064</FONT>         * Constructs a new empty &lt;code&gt;ArrayStack&lt;/code&gt; with an initial size.<a name="line.64"></a>
<FONT color="green">065</FONT>         * <a name="line.65"></a>
<FONT color="green">066</FONT>         * @param initialSize  the initial size to use<a name="line.66"></a>
<FONT color="green">067</FONT>         * @throws IllegalArgumentException  if the specified initial size<a name="line.67"></a>
<FONT color="green">068</FONT>         *  is negative<a name="line.68"></a>
<FONT color="green">069</FONT>         */<a name="line.69"></a>
<FONT color="green">070</FONT>        public ArrayStack(int initialSize) {<a name="line.70"></a>
<FONT color="green">071</FONT>            super(initialSize);<a name="line.71"></a>
<FONT color="green">072</FONT>        }<a name="line.72"></a>
<FONT color="green">073</FONT>    <a name="line.73"></a>
<FONT color="green">074</FONT>        /**<a name="line.74"></a>
<FONT color="green">075</FONT>         * Return &lt;code&gt;true&lt;/code&gt; if this stack is currently empty.<a name="line.75"></a>
<FONT color="green">076</FONT>         * &lt;p&gt;<a name="line.76"></a>
<FONT color="green">077</FONT>         * This method exists for compatibility with &lt;code&gt;java.util.Stack&lt;/code&gt;.<a name="line.77"></a>
<FONT color="green">078</FONT>         * New users of this class should use &lt;code&gt;isEmpty&lt;/code&gt; instead.<a name="line.78"></a>
<FONT color="green">079</FONT>         * <a name="line.79"></a>
<FONT color="green">080</FONT>         * @return true if the stack is currently empty<a name="line.80"></a>
<FONT color="green">081</FONT>         */<a name="line.81"></a>
<FONT color="green">082</FONT>        public boolean empty() {<a name="line.82"></a>
<FONT color="green">083</FONT>            return isEmpty();<a name="line.83"></a>
<FONT color="green">084</FONT>        }<a name="line.84"></a>
<FONT color="green">085</FONT>    <a name="line.85"></a>
<FONT color="green">086</FONT>        /**<a name="line.86"></a>
<FONT color="green">087</FONT>         * Returns the top item off of this stack without removing it.<a name="line.87"></a>
<FONT color="green">088</FONT>         *<a name="line.88"></a>
<FONT color="green">089</FONT>         * @return the top item on the stack<a name="line.89"></a>
<FONT color="green">090</FONT>         * @throws EmptyStackException  if the stack is empty<a name="line.90"></a>
<FONT color="green">091</FONT>         */<a name="line.91"></a>
<FONT color="green">092</FONT>        public Object peek() throws EmptyStackException {<a name="line.92"></a>
<FONT color="green">093</FONT>            int n = size();<a name="line.93"></a>
<FONT color="green">094</FONT>            if (n &lt;= 0) {<a name="line.94"></a>
<FONT color="green">095</FONT>                throw new EmptyStackException();<a name="line.95"></a>
<FONT color="green">096</FONT>            } else {<a name="line.96"></a>
<FONT color="green">097</FONT>                return get(n - 1);<a name="line.97"></a>
<FONT color="green">098</FONT>            }<a name="line.98"></a>
<FONT color="green">099</FONT>        }<a name="line.99"></a>
<FONT color="green">100</FONT>    <a name="line.100"></a>
<FONT color="green">101</FONT>        /**<a name="line.101"></a>
<FONT color="green">102</FONT>         * Returns the n'th item down (zero-relative) from the top of this<a name="line.102"></a>
<FONT color="green">103</FONT>         * stack without removing it.<a name="line.103"></a>
<FONT color="green">104</FONT>         *<a name="line.104"></a>
<FONT color="green">105</FONT>         * @param n  the number of items down to go<a name="line.105"></a>
<FONT color="green">106</FONT>         * @return the n'th item on the stack, zero relative<a name="line.106"></a>
<FONT color="green">107</FONT>         * @throws EmptyStackException  if there are not enough items on the<a name="line.107"></a>
<FONT color="green">108</FONT>         *  stack to satisfy this request<a name="line.108"></a>
<FONT color="green">109</FONT>         */<a name="line.109"></a>
<FONT color="green">110</FONT>        public Object peek(int n) throws EmptyStackException {<a name="line.110"></a>
<FONT color="green">111</FONT>            int m = (size() - n) - 1;<a name="line.111"></a>
<FONT color="green">112</FONT>            if (m &lt; 0) {<a name="line.112"></a>
<FONT color="green">113</FONT>                throw new EmptyStackException();<a name="line.113"></a>
<FONT color="green">114</FONT>            } else {<a name="line.114"></a>
<FONT color="green">115</FONT>                return get(m);<a name="line.115"></a>
<FONT color="green">116</FONT>            }<a name="line.116"></a>
<FONT color="green">117</FONT>        }<a name="line.117"></a>
<FONT color="green">118</FONT>    <a name="line.118"></a>
<FONT color="green">119</FONT>        /**<a name="line.119"></a>
<FONT color="green">120</FONT>         * Pops the top item off of this stack and return it.<a name="line.120"></a>
<FONT color="green">121</FONT>         *<a name="line.121"></a>
<FONT color="green">122</FONT>         * @return the top item on the stack<a name="line.122"></a>
<FONT color="green">123</FONT>         * @throws EmptyStackException  if the stack is empty<a name="line.123"></a>
<FONT color="green">124</FONT>         */<a name="line.124"></a>
<FONT color="green">125</FONT>        public Object pop() throws EmptyStackException {<a name="line.125"></a>
<FONT color="green">126</FONT>            int n = size();<a name="line.126"></a>
<FONT color="green">127</FONT>            if (n &lt;= 0) {<a name="line.127"></a>
<FONT color="green">128</FONT>                throw new EmptyStackException();<a name="line.128"></a>
<FONT color="green">129</FONT>            } else {<a name="line.129"></a>
<FONT color="green">130</FONT>                return remove(n - 1);<a name="line.130"></a>
<FONT color="green">131</FONT>            }<a name="line.131"></a>
<FONT color="green">132</FONT>        }<a name="line.132"></a>
<FONT color="green">133</FONT>    <a name="line.133"></a>
<FONT color="green">134</FONT>        /**<a name="line.134"></a>
<FONT color="green">135</FONT>         * Pushes a new item onto the top of this stack. The pushed item is also<a name="line.135"></a>
<FONT color="green">136</FONT>         * returned. This is equivalent to calling &lt;code&gt;add&lt;/code&gt;.<a name="line.136"></a>
<FONT color="green">137</FONT>         *<a name="line.137"></a>
<FONT color="green">138</FONT>         * @param item  the item to be added<a name="line.138"></a>
<FONT color="green">139</FONT>         * @return the item just pushed<a name="line.139"></a>
<FONT color="green">140</FONT>         */<a name="line.140"></a>
<FONT color="green">141</FONT>        public Object push(Object item) {<a name="line.141"></a>
<FONT color="green">142</FONT>            add(item);<a name="line.142"></a>
<FONT color="green">143</FONT>            return item;<a name="line.143"></a>
<FONT color="green">144</FONT>        }<a name="line.144"></a>
<FONT color="green">145</FONT>    <a name="line.145"></a>
<FONT color="green">146</FONT>        /**<a name="line.146"></a>
<FONT color="green">147</FONT>         * Returns the one-based position of the distance from the top that the<a name="line.147"></a>
<FONT color="green">148</FONT>         * specified object exists on this stack, where the top-most element is<a name="line.148"></a>
<FONT color="green">149</FONT>         * considered to be at distance &lt;code&gt;1&lt;/code&gt;.  If the object is not<a name="line.149"></a>
<FONT color="green">150</FONT>         * present on the stack, return &lt;code&gt;-1&lt;/code&gt; instead.  The<a name="line.150"></a>
<FONT color="green">151</FONT>         * &lt;code&gt;equals()&lt;/code&gt; method is used to compare to the items<a name="line.151"></a>
<FONT color="green">152</FONT>         * in this stack.<a name="line.152"></a>
<FONT color="green">153</FONT>         *<a name="line.153"></a>
<FONT color="green">154</FONT>         * @param object  the object to be searched for<a name="line.154"></a>
<FONT color="green">155</FONT>         * @return the 1-based depth into the stack of the object, or -1 if not found<a name="line.155"></a>
<FONT color="green">156</FONT>         */<a name="line.156"></a>
<FONT color="green">157</FONT>        public int search(Object object) {<a name="line.157"></a>
<FONT color="green">158</FONT>            int i = size() - 1;        // Current index<a name="line.158"></a>
<FONT color="green">159</FONT>            int n = 1;                 // Current distance<a name="line.159"></a>
<FONT color="green">160</FONT>            while (i &gt;= 0) {<a name="line.160"></a>
<FONT color="green">161</FONT>                Object current = get(i);<a name="line.161"></a>
<FONT color="green">162</FONT>                if ((object == null &amp;&amp; current == null) ||<a name="line.162"></a>
<FONT color="green">163</FONT>                    (object != null &amp;&amp; object.equals(current))) {<a name="line.163"></a>
<FONT color="green">164</FONT>                    return n;<a name="line.164"></a>
<FONT color="green">165</FONT>                }<a name="line.165"></a>
<FONT color="green">166</FONT>                i--;<a name="line.166"></a>
<FONT color="green">167</FONT>                n++;<a name="line.167"></a>
<FONT color="green">168</FONT>            }<a name="line.168"></a>
<FONT color="green">169</FONT>            return -1;<a name="line.169"></a>
<FONT color="green">170</FONT>        }<a name="line.170"></a>
<FONT color="green">171</FONT>    <a name="line.171"></a>
<FONT color="green">172</FONT>        /**<a name="line.172"></a>
<FONT color="green">173</FONT>         * Returns the element on the top of the stack.<a name="line.173"></a>
<FONT color="green">174</FONT>         *<a name="line.174"></a>
<FONT color="green">175</FONT>         * @return the element on the top of the stack<a name="line.175"></a>
<FONT color="green">176</FONT>         * @throws BufferUnderflowException  if the stack is empty<a name="line.176"></a>
<FONT color="green">177</FONT>         */<a name="line.177"></a>
<FONT color="green">178</FONT>        public Object get() {<a name="line.178"></a>
<FONT color="green">179</FONT>            int size = size();<a name="line.179"></a>
<FONT color="green">180</FONT>            if (size == 0) {<a name="line.180"></a>
<FONT color="green">181</FONT>                throw new BufferUnderflowException();<a name="line.181"></a>
<FONT color="green">182</FONT>            }<a name="line.182"></a>
<FONT color="green">183</FONT>            return get(size - 1);<a name="line.183"></a>
<FONT color="green">184</FONT>        }<a name="line.184"></a>
<FONT color="green">185</FONT>    <a name="line.185"></a>
<FONT color="green">186</FONT>        /**<a name="line.186"></a>
<FONT color="green">187</FONT>         * Removes the element on the top of the stack.<a name="line.187"></a>
<FONT color="green">188</FONT>         *<a name="line.188"></a>
<FONT color="green">189</FONT>         * @return the removed element <a name="line.189"></a>
<FONT color="green">190</FONT>         * @throws BufferUnderflowException  if the stack is empty<a name="line.190"></a>
<FONT color="green">191</FONT>         */<a name="line.191"></a>
<FONT color="green">192</FONT>        public Object remove() {<a name="line.192"></a>
<FONT color="green">193</FONT>            int size = size();<a name="line.193"></a>
<FONT color="green">194</FONT>            if (size == 0) {<a name="line.194"></a>
<FONT color="green">195</FONT>                throw new BufferUnderflowException();<a name="line.195"></a>
<FONT color="green">196</FONT>            }<a name="line.196"></a>
<FONT color="green">197</FONT>            return remove(size - 1);<a name="line.197"></a>
<FONT color="green">198</FONT>        }<a name="line.198"></a>
<FONT color="green">199</FONT>    <a name="line.199"></a>
<FONT color="green">200</FONT>    }<a name="line.200"></a>




























































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